1. Field of the Invention
This invention relates to substituted 3-(.alpha.,.alpha.-dimethylbenzyl)urea compounds, to methods of the preparation thereof, to herbicidal compositions containing such compounds, and to a method for controlling weed growth employing these compounds and compositions.
2. Description of the Prior Art
Various urea derivatives have been proposed as herbicides since fenuron, monuron, diuron, etc., were developed at the beginning of the 1950's. However, most of the compounds whose herbicidal activities have been confirmed and which have been practically used are those having a phenylurea type chemical structure. Very few compounds are of the aralkylurea type, as described in Floyd M. Ashton et al., Table 21-1, Urea Type Herbicides in General Use, Mode of Action of Herbicides, Wiley-Interscience, p. 369. That is, most of the urea derivatives presently used as herbicides have a chemical structure where a phenyl group or a substituted phenyl group is directly attached to at least one of the nitrogen atoms of a urea skeleton.
Hitherto, some of the prior art references describe aralkylurea type herbicides, for example, U.S. Pat. Nos. 3,388,158, 3,483,296 and 3,660,484, but none of these patents discloses that compounds having an .alpha.,.alpha.-dimethylbenzylurea structure, which is a characteristic chemical structure of the compounds of this invention, are useful as herbicides. Chemical Abstracts, 43, 6993i (1949) describes a specific compound, N-(.alpha.,.alpha.dimethylbenzyl)-N'-phenylurea, but does not teach nor suggest the chemical properties and biological activities of this compound.
Some of the co-inventors of the present invention previously filed U.S. patent applications, i.e., U.S. patent application Ser. Nos. 597,137 filed on July 18, 1975 and 518,812 filed on Oct. 29, 1974 (now patented as U.S. Pat. No. 3,972,909, issued on Aug. 3, 1976), both relating to .alpha., .alpha.-dimethylbenzylureas and their applications as herbicides, and they also reported the same .alpha., .alpha.-dimethylbenzylureas and their activities in "Selective Control of Cyperaceous Weeds with K-223", Weed Science, 23, pp. 18-19, Jan. 1975, but these compounds differ from the compounds of this invention in the type of substituents, such as halogen atoms, attached to the phenyl moiety of the .alpha., .alpha.-dimethylbenzyl group.